Vacuum Motor Test

Check all hoses for damage. With engine not running, observe position of damper door through snorkel. Door should be in such a position that heat stove passage is covered. If not, check for binds in linkage. Apply at least 9" of vacuum to diaphragm assembly through hose disconnected at sensor unit. Damper door should completely close snorkel passage when vacuum is applied. With vacuum applied, clamp hose to trap vacuum in diaphragm assembly. Snorkel passage should remain closed, if not, there is a leak in diaphragm assembly.